Yorkshire Building Society is set to enter the flexible mortgage market and sell products direct over the phone later this year.
It is spending £19m to upgrade computer systems, allowing the society to offer more complex products such as flexible mortgages.
Flexible mortgages allow borrowers to take repayment holidays and make overpayments. They have become increasingly popular over the last few years.
Yorkshire is also joining the rush of high-street lenders selling mortgages over the phone. Communications manager David Holmes says: "We want to go into mortgages over the phone this year. It is still only 5 per cent of the market but it is an increasingly high-net-worth and low-loan-to-value market and we all want to get a part of that.
"We will also move into the flexible mortgage market. We are updating our compu ter systems so we can offer any type of mortgage product."
Other lenders, including Halifax and Alliance & Leicester, are working on plans to sell a clutch of products over the phone this year, includ ing mortgages and pensions.
But Yorkshire denies it is considering a move into pensions. It withdrew from selling financial services products through its branches in 1995, claiming it was too expensive.
Yorkshire ditched its 37-strong IFA division in October 1995. It is the fourth-biggest building society with mortgage assets of about £6.7bn.